2. So, what is driver of printer?

Driver of printer is an software interaction between printer and computer.
This software help your computer can be communicate with printer through cable USB. Printer will be receive the command print from computer and on the smart panel (status windows) of computer will be display the error message. For example: Toner low, Toner empty, Toner exhausted, LSU error, Fuser error, Scanner error …
If you install driver of your printer be wrong then the printer can not print, don’t show error massage as well as action status.
Therefore, you must be to install driver of your printer are correctly to help the printer functioning properly

3. Install driver of Brother MFC-9800 printer guide

Some people don’t know how to install driver (software interaction) of printer although they were downloaded driver of printer.
The following is Video guide to install driver of Brother MFC-9800 printer.